Sweetening of hydrocarbon distillates



United States Patent SWEETENING 0F HYDROCARBON DISTILLATES Joseph A. Chenicek, Prairie View, 111., assignor, by mesne assignments, to Universal Oil Products Company, Des Plaines, 11]., a corporation of Delaware No Drawing. Application October 31, 1957 Serial No. 693,561

7 Claims. (Cl. 208-204) tillate with an alkali metal hydroxide solution and particularly sodium hydroxide solution, potassium hydroxide solution, etc. A modification of this process includes the use of a solubilizer along with the alkali metal hydroxide solution. These and other methods are satisfactory for removing a major proportion of the mercaptans from the hydrocarbon distillate. However, the hydrocarbon distillate still contains mercaptans and is not sweet to the Doctor test. A recent process effects the final sweetening of the distillate by incorporating therein a phenylene diamine compound.

In accordance with the presentinvention, the final sweetening of the hydrocarbon distillate is effected by incorporating therein a compound of difierent chemical structure and by means of a different chemical mechanism than heretofore utilized for this purpose.

In one embodiment the present invention relates to a method of sweetening a sour hydrocarbon distillate which comprises incorporating in said distillate and reacting with the mercaptans contained therein a compound having the general formula:

where R is selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, alkaryl and cycloalkyl, and X is selected from the group consisting of 'NOI, -c OEN, and -s0,R'

and R is selected from a group consisting of hydrogen, alkyl, aryl, aralkyl, alkaryl, cycloalkyl, hydroxy and alkoxy. I

Referring to the above formula, where X is a -NO:, the compound will comprise a nitroalkylene, nitrostyrene, etc. compound. Nitroalkylene compounds include nitroethylene, l-nitro-l-propene, l-nitro-l-butene, l-nitro-lpentene, l-nitro-l-hexene, l-nitro-l-heptene, l-nitro-loctene, etc. Nitrostyrene having the configuration set forth above is omega-nitrostyrene and is a preferred compound for use in accordance with the present invention. Other similar nitro compounds include omega-nitroallylbenzene, omega-nitrophenylbutadiene, etc.

When X in the above formula is a the compound will be an unsaturated aldehyde including acrolein, crotonaldehyde, cinnamaldehyde, etc.

2,893,952 Patented July 7, 1959 When X in. the above formula is a =N, the compound will comprise acrylonitrile, methylacrylonitrile, ethylacrylonitrile, propylacrylonitrile, butylacrylonitrile, etc. When X is a group, the compound will comprise an unsaturated sulfone including, for example, compounds as vinylsulfone, betamethylvinyl sulfone, beta-dimethylvinyl sulfone, betaethylvinyl sulfone, beta-propylvinyl sulfone, beta-butylvinyl sulfone, beta-phenylvinyl sulfone, beta-tolylvinyl sulfone, beta-xylylvinyl sulfone, vinylmethyl sulfone, vinylethyl sulfone, vinylpropyl sulfone, vinylbutyl sulfone, beta-methylvinyl-methyl sulfone, beta-di-methylvinylmethyl sulfone, beta-methylvinyl-ethyl sulfone, betamethylvinyl-propyl sulfone, beta-methylvinyl-butyl sulfone, etc.

It is understood that the various compounds which may be utilized for reacting with the mercaptans in the hydrocarbon distillate are not necessarily equivalent and that some may be'more elfective than others in certain hydrocarbon distillates. It also is understood that a mixture of 2 or more of these compounds may be employed.

In effecting sweetening of the sour distillate, the compound reacts with the mercaptans in the sour distillate. It is believed that the reaction proceeds as illustrated in the following equation, although it is not intended that applicant shall be limited to this specific explanation.

In the above equation R represents the groups as hereinbefore set forth. R" represents a hydrocarbon or substituted hydrocarbon group corresponding to the mercaptan or mercapto compound present in the hydrocarbon distillate.

Another advantage to the novel process of the present invention is that the reaction product possesses antioxidant properties and, therefore, will improve the stability of the hydrocarbon distillate in retarding and/or preventing gum formation, discoloration, etc.

In another embodiment, the novel method of the present invention may be utilized in conjunction with the use of a phenylene diamine compound. The phenylene diamine compound eifects final sweetening very readily in most cases. However, in some cases, the sweetening is accompanied by the formation of peroxides and gum. In such cases, the use of the compound of the present invention along with the phenylene diamine compound will serve to obtain the desired sweetening without formation of undesirable peroxides and gums. In other cases, the use of both the compound of the present invention and the phenylene diamine will serve to obtain the desired sweetening in distillates which are not readily sweetened by phenylene diamine alone. Of the phenylene diamines, N,N'-di-sec-butyl-p-phenylene diamine is preferred. Other phenylene diamine compounds include pphenylene diamines in which the alkyl substituents attached to the nitrogen atoms each contain from 1 to about 12 carbon atoms. When utilizing the phenylene diamine compound, it is necessary that oxygen is present, and the oxygen may be dissolved in the hydrocarbon distillate or, if an insuflicient amount is present in this manner, air may be added to the hydrocarbon distillate in any suitable manner. The phenylene diamine comabout -0.0001% to about 0. 5% -by weight and also serves as an antioxidant in the hydrocarbon distillate.

The sweetening of the hydrocarbon distillate may be eitectedin any suitable manner. in one embodiment, the sweetening is effected the presence of an alkali metal hydroxide. When the hydrocarbon distillate is first treated with an alkali metal hydroxide to remove a major proportion of the mercaptan, the treated hydrocarbon distillate will contain a small amount of entrained alkali metal hydroxide. In many cases this small amount of alkali metal hydroxide is suflicient for the purpose and the sweetening with the compound of the present inventie is e ected in the P ese ce he e In anoth meth it may be irab o ad alka m t ydrox d to the hydrocarbon distillate before oratter the addition of the compound ofthe presentinvention. In place or in add t n t the alk l meta hydroxid gani m n compounds may .be utilized including, for example, piperidine, etc. When the phenylene .diaminecompound is utilized, air may be bubbled through the hydrocarbon distillate containing the additives to thereby insure intimate mixing and to accelerate the sweetening.

In effecting the sweetening with the compound of the present invention, it generally is preferred to obtain intimate mixing of .thecompound of the present invention with the y carb n di i l e .In one method, the compound of the present invention is commingled with the hydrocarbon distillate and the resultant mixture is passed through suitable mixing devices such as durion mixers, orifice mixers, etc. The resultant mixture then is introduced into a storage tank Which, when vdesired, may contain suitable stirring means such as mixing paddles, et toeffec f ther mix ng- The weete ng is readily eifected at atmospheric temperature, although elevated temperatures up to 220 F. or more may be utilized when desired. The amount of compound of the present invention to be employed will depend upon the mercaptan content of the hydrocarbon distillate. At least one molecular proportion of compound of the present invention per molecular proportion of mercaptan should be employed. Usually it is desired to employ at least a slight excess of compound of the present invention in order to insure complete reaction and thus may range up to or more molecular proportions of compound of the present invention per molecular proportion of mercaptan. In general, the concentration of compound of the present invention may range from 0.0001% to 2% or more by weight of the hydrocarbon distillate and preferably in a concentration of from about 0.001% to about 0.5% by weight.

The process of the present invention may be used to eifect sweetening ofany sour hydrocarbon distillate and is particularly applicable to the treatment of gasoline and more particularly-cracked gasoline. However, it may be utilized for-the treatment of straight ru1 1 gasoline,mixtures of cracked and straight run gasoline,-crached and/ or straight run higher boiling distillates including kerose'ne, diesel oil, fuel oil, gas oil, etc.

As hereinbefore set forth, the compound of the present invention may be utilized along with phenylene diarnine compound. It is understood that the compound of the present invention also may be utilized along with other additives which are addedto' the hydrocarbon distillate for specific purposes including other antioxidants, metal deactivators, dyes, etc. When desired the compound of the present invention may be utilized in a suitable-solvent or it may comprise the' solvent for other additives and thus serve adual function. As an example, N,N'-disecbutyl-p-phenyl e'ne dianiine may be prepared as asolution in acrylonitrile, and this solution is added to the hydrocarbon distillate.

The following examples are introduced to illustrate furthe; the novelty and futility of the present invention-but not withthe intention of unduly lirhiting the same.

The gasoline used in this example was a thermally cracked gasoline having an original mercaptan sulfur content of 0.005% by weight, which was increased to 0.03% by the addition of n-hexyl mercaptan. Omega-nitrostyrene was added to a sample of the gasoline in a molar ratio of 10:1 to mercaptan. After suitable mixing and a'residence time of 24 hours .at .68- F., the -mercaptan een ente theg e n was ecreas Example II Sweetening was efiected with omega-nitrostyrene in the same main-ner .as described in Example 1 .except that a temperature of 212 F. was employed. When using the higher temperature, .the mercaptan content of the gasoline was decreased 92% after 20 minutes.

Example III sweetening with omega-nitrostyrenein the same manner described in Example I except that the sweetening was effected in the presence of sodium hydroxide. The molar ratio of omega-nitrostyrene to mercaptan 5 :1. After -24 hours, the mercaptan content of the gasoline was decreased 91%.

Examp IV The compound used in this example was acrolein. When added ina molar proportion of 5:1 to mercaptan, acrolein served toadecrease the mercaptan 7 content .of the gasoline 66% after 24-hours at 68 F.

Example V The compound used in this example is acrylonitrile.

1 It is added in a molar ratio of 7:1 to sour kerosene'and is reacted in the presence of piperidi-ne at a temperature of F. This serves to decrease the mercaptan content of the kerosene.

Example VI The compound used inthis example is vinylsulfone. It is added-in a molar ratio of '821 to sour cracked gasoline and is reacted in thepresence of potassiumhydrox-ide at a-tem-perature of F, This selves to decreasethe mercaptan content of the gasoline.

I claim as my invention:

1. A method of sweetening a sour hydrocarbon distillate containing mercapta-ns which comprises incorporating in said distillate and reacting with the mercaptans contained therein from about 0.0001% toabout 2% by weight of a compound having the general formula:

RC=CX where R is selected'from the group consisting of hydrogen, alkyl, aryl, aralkyl, alkaryl and cycloalkyl, and X i selecte fre th oup consistin of and R is selected from a group consisting of hydrogen, alkyl, aryl, 'aralkyl, alkaryl, cycloa'liiyl, hydroxy and alkoxy, effecting said reaction at a temperature of from about atmospheric to about 220 F. and recovering a sweetened distillate.

2. The method of claim 1 further characterized inthat said-reacting iseffccted in-the presence of an alkali metal hydroxide. V

3. The process of claim l-further characterized in that said reacting is effected in the presence of a phenylenc diamine compound.

4. A method of sweetening a gasoline containing mercaptans which comprises incorporating in said gasoline and reacting with the 'mercaptans contained therein from about 0.0001% to about 2% by Weight of omega-nitrostyrene, eifecting said reaction at a temperature of from about atmospheric to about 220 F. in the presence of sodium hydroxide and recovering a sweetened gasoline.

5. A method of sweetening a gasoline containing mercaptans which comprises incorporating in said gasoline and reacting with the mercaptans contained therein from about 0.0001% to about 2% by weight of acrolein, effecting said reaction at a temperature of from about atmospheric to about 220 F. in the presence of sodium hydroxide and recovering a sweetened gasoline.

6. A method of sweetening a gasoline containing mercaptans which comprises incorporating in said gasoline and reacting with the mercaptans contained therein from about 0.0001% to about 2% by weight of acrylonitrile, efiecting said reaction at a temperature of from about atmospheric to about 220 F. in the presence of sodium hydroxide and recovering a sweetened gasoline.

7. A method of sweetening a gasoline containing mercaptans which comprises incorporating in said gasoline and reacting with the mercaptans contained therein from about 0.0001% to about 2% by weight of vinyl sulfone, efiecting said reaction at a temperature of from about atmospheric to about 220 F. in the presence of sodium hydroxide and recovering a sweetened gasoline.

References Cited in the file of this patent UNITED STATES PATENTS 1,601,215 Johansen Sept. 28, 1926 2,033,877 Burk Mar. 10, 1936 2,176,747 Schneider et al Oct. 17, 1939 2,354,646 Bell Aug. 1, 1944 2,357,344 Morris et a1 Sept. 5, 1944 2,415,817 Fetterly Feb. 18, 1947 2,432,301 Fetterly Dec. 9, 1947 2,492,334 Thompson Dec. 27, 1949 2,496,444 Cook Feb. 7, 1950 2,616,832 Browder Nov. 4, 1952 2,684,943 Baker July 27, 1954 

1. A METHOD OF SWEETENING A SOUR HYDROCARBON DISTILLATE CONTAINING MERCAPTANS WHICH COMPRISES INCORPORATING IN SAID DISTILLATE AND REACTING WITH THE MERCAPTANS CONTAINED THEREIN FROM ABOUT 0.0001% TO ABOUT 2% BY WEIGHT OF A COMPOUND HAVING THE GENERAL FORMULA: 